STUDY OF RESONANCE PHENOMENA WHEN CONNECTING 0.38 KV BATTERIES OF TRANSVERSE COMPENSATION CAPACITORS TO THE NETWORK

Abstract

The article deals with the operation of capacitor banks as part of regulated capacitor units connected to the 0.38 kV electrical network of power transformers of 10/0.4 kV consumer substations. It is known that capacitor banks are used to compensate for the reactive power of electrical receivers and equalize the load of phases in three-phase four-wire networks of 0.30 kV by creating reverse sequence currents equal in magnitude, but rotated by 1800 relative to the load currents due to the inclusion of a different number of capacitors between the network phases. The wide presence of non-linear electrical receivers in electric networks causes the occurrence of higher harmonic components of voltage and current, which cause an increase in the current in capacitors, since the reactive resistance of capacitors decreases with increasing frequency. At the same time as the current in the capacitors increases, which can be regulated with the help of constructive measures, in unfavorable cases resonance phenomena may occur in the networks. Widespread use of capacitor banks creates risks of resonance of voltages and currents both at the main frequency of three-phase alternating current of 50 Hz and at frequencies of 150, 250, 350 and 550 Hz due to higher harmonic components of voltage and current. The obtained results indicate that for the resonance of currents to occur at the main frequency for power transformers of different capacities, the power of the capacitor banks should be from 0.02 kV×Ar per 1 kV×A of power (for a 630 kV×A transformer) to 0.034 kV×Ar (for a 25 kV×A transformer), and for the occurrence of voltage resonance, respectively, from 18.7 kV×Ar/kV×A to 26 kV×Ar/kV×A. In addition, calculations show that to increase the power factor even by a small amount (from 0.9 to 0.95), it is necessary to install capacitor banks of at least 0.14 kV×Ar/kV×A, and to increase the power factor from 0, 7 to 0.95 - only 0.66 kV×Ar/kV×A.